Method for Repairing Metallic Structure

ABSTRACT

A rail repair method enables repair of rails and rail-like structures. A rail defect is initially identified and removed as contained within a volumetric material portion so as to form a contoured void while maintaining continuity of the rail opposite the void. A pre-formed insert is then placed into the void thereby effecting a rail-to-insert interface. Current is driven through the interface as force directs the insert against the rail. Resistance heat and pressure weld the insert to the rail. The flash welding aspects remove oxides and other impurities from the interface, and the forge welding aspects create a robust solid state weld. Excess material, whether flash, rail, or insert-based, is removed during the finishing processes to provide a virtually seamless rail repair. The solid state weld repair methodology may be used to repair any number of targeted metallic rail-like structures.

PRIOR HISTORY

This non-provisional patent application is a divisional patentapplication of pending U.S. patent application Ser. No. 12/661,965 filedin the United States Patent and Trademark Office on 26 Mar. 2010, thespecifications of which are hereby incorporated by reference thereto.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to a method of repairing targeteddefect-containing metallic structure, and more particularly to a methodof repairing railroad rail having a localized defect in the top portionof the rail, which methodology involves the step of removing adefect-containing top portion of the rail, replacing the removed portionof the rail by welding in a solid state weld repair insert.

2. Description of Prior Art

Railroads must maintain their track to ensure safe operation of trains.Some of this maintenance centers on the repair of rail defects. Railroadrails may be manufactured with internal defects or, as a result offatigue, develop defects. These defects are commonly located usingnon-destructive test methods. The Federal Railway Administration (FRA),for example, mandates periodic ultrasonic testing of railroad rails tolocate defects in the rail. When a defect is found, a repair must bemade to the track structure. It has been noted that many of thesedefects are located in the top portion of the rail or within the railhead.

There are two common welding processes used to facilitate the repair ofdefects in railroad rails. These processes are the thermite weldingprocess and the flash-butt welding process. Rails repaired by aflash-butt weld are typically stronger and higher in quality than thoserepaired by a thermite weld. Repairs made by the thermite process areinitially less costly, however, due to the relatively higher labor andequipment or components cost(s) required by the flash-butt process.Rails may also be temporarily repaired through the use of joint barsplices. Overall rail integrity is best maintained, however, by havingthe lowest number of joints (mechanical or welded) in track.

State of the art rail repair directed at repairing defects has typicallyinvolved removing a length of rail, (typically 13 to 19 feet in length)localized around the defect, from the existing rail. The removal of therail length thus creates a significant gap in the rail. A so-called“rail plug” is then inserted in the resulting gap to make up for thebulk of the rail length removed. A weld is then made at each end of therail plug, welding the rail plug to the existing rail, and creating acontinuously welded rail.

A thermite weld can be used to weld the existing rail to the rail plug.A rail plug is cut to a length approximately two inches shorter than thelength of the rail containing the defect, which is being cut out. Therepair plug is placed into the gap. A sand mold is attached to both theexisting rail and the rail plug around an approximate one-inch gapbetween the end of the existing rail and the end of the rail plug. Thethermite material is contained in a crucible located immediately abovethe sand mold. After the mold is pre-heated, the thermite charge isignited. The thermite charge creates molten steel, which pours into thesand mold.

As the thermite material solidifies, it forms a casting, which bonds to,and is contiguous with, both the existing rail and the rail plug. Inthis manner, the rail plug is welded to the existing rail to form acontinuous section. A second thermite weld is made at an approximateone-inch gap at the opposite end of the rail plug, joining the rail plugto the existing rail. The area of the rail containing the thermite weldmaterial is not as strong as and is not of the same quality as normalrail steel. As such, the thermite welds typically require subsequentrepairs in order to maintain the railroad rail in safe condition. Thismethod also requires the repair crew to transport a rail plug to therepair site and the section of rail containing the defect away from thesite.

A flash-butt weld can also be used to weld the existing rail to the railplug. A rail plug is cut to a length approximately three inches longerthan the length of the rail containing the defect, which is being cutout. Rail anchors are removed from the existing rail until the gapcreated by the removal of the defect containing rail plug is threeinches longer than the defect containing rail plug. This can only occurwhen the current rail temperature (CRT) is below the neutral railtemperature (NRT). The rail plug is put in to the gap created by theremoval of the defect containing rail plug and gap growth created by theremoval of anchors.

The rail ends to be welded are aligned. A flash-butt weld welderhead isclamped across the abutment of the rail plug and the existing rail, andthe flash-butt welding cycle is carried out. The welderhead passes ahigh current across the interface between the existing rail and the railplug. The current produces arcing between the mating surfaces. As thecycle progresses and sufficient heat has been generated, the welderheadforges the two pieces of rail together to essentially form a singlecontinuous rail. A shear die is then pushed across the weld to returnthe weld profile to the rail contour. The flashing away of the rail andthe forging of the rail consume about one and one half inches of railfrom the rail and the rail plug.

The rail ends at the other end of the rail plug are aligned. Theflash-butt welderhead is moved to the other end of the rail plug andclamped across the abutment of the rail plug and the existing rail. Therails are stretched to close the gap (which was generated by the makingof the initial weld and subsequent moving the rail plug) and theflash-butt weld cycle is carried out. Rail anchors are then replaced onto the existing rail. As such, the flash-butt welding process istypically more costly than the thermite process. This method alsorequires the repair crew to transport a rail plug to the repair site andthe section of rail containing the defect away from the site.

Regardless of the repair weld process used, there is a need to maintainthe NRT. The NRT is the temperature at which the rail contains nolongitudinal thermally-induced rail stresses. The track is designed tonot allow the rails to contract and expand in response to environmentaltemperature changes. It is designed to constrain the rail and allow therail to develop tension and compression. The amount of tension orcompression is determined, in part, by the difference between NRT andthe CRT.

When a repair is accomplished by installing a rail plug, it is unlikelythat the rail plug installed will be of the exact length necessary tomaintain the NRT of the rail, and the NRT of the rail is thus altered.As such, the segment will have a different NRT than desired. Notably,management of the NRT could be simplified if no rail length is removedduring the repair of a defect in the rail.

It is further noted that when rail plugs are installed using either thethermite weld or the flash-butt weld processes, the rail is taken out ofservice. Thermite welding and flash-butt welding trucks need to occupythe track. This prevents the railroad from running revenue-producingtrains. The installation of a rail plug and the resulting two necessarywelds uses valuable track time and this repair time needs to be kept toa minimum.

Joint bar splices are, essentially, reinforcing clamp means applied tothe rail adjacent to the repair. A joint bar splice is used when thereis not enough time to perform a complete repair by welding or when otherrepair materials are not available. A joint bar splice, by governmentregulation, is a temporary repair and must be replaced in about 90 days.The joint bar splice thus reduces the operational limit of the rail inthe repair area.

U.S. Pat. No. 7,520,415, which issued to Kral et al. discloses a furtherMethod of Repairing Rail, which disclosure attempted to address thenoted rail repair shortcomings. The '415 Patent describes a system ormethod comprising at least the following steps: identifying and locatinga defect in the rail, removing the defect by removing material from therail surrounding the defect in at least the head section so as to form avoid and a rail void interface while maintaining continuity of the rail,filling the void with molten metal having a high carbon content andcausing the molten metal and the rail void interface to bond.

The molten metal may be produced by gas shielded arc welding. The carboncontent of the molten metal is near that of the rail to decrease carbonmigration from the rails. High carbon welding electrode is used in thewelding of high strength steel using gas shielded arc welding techniqueswhereby a plurality of beads of molten weld material join together railends or fill a slot in a rail for repair purposes. The high carbonelectrode avoids producing adjacent soft and brittle areas across a weldfusion line, which results from migration of carbon from the carbon richhigh strength steel to the lower carbon and highly alloyed weld deposit.

The foregoing methodology described by Kral et al., while notablysuperior to certain aspects of the thermite and flash-butt railrepair/welding techniques described hereinabove, nevertheless alsosuffers from certain shortcomings. In this regard, it is noted that themolten metal material is a dynamically active medium, which mediumpresents certain difficulties in (non-ideal) application scenarios. Forexample, if the rail is inclined in the field, the molten pool ofmaterial becomes difficult to manage, and a proper weld is oftenproblematic to achieve without much ado.

The prior art thus perceives a need for a rail repair method thatresults in a rail repair having the strength and quality of the parentrail, but without adding or consuming rail. Further, the prior perceivesa need for a rail repair method which reduces the total number of weldsin the remaining rail. Still further, the prior art perceives a need fora rail repair method which reduces the amount of materials and equipmentthat must be transported to and from the repair site.

Other prior art needs include a need for a rail repair method thateliminates the use of temporary joint bar splices. The prior art furtherperceives a need for a rail repair method that does not necessitate therelatively costly and time-consuming removal of a section of rail. Thepresent invention attempts to address the foregoing by providing a costeffective, time-efficient rail repair method which minimizes the amountof time that the rail is out of service to revenue-producing trains, andwhich method greatly reduces the manpower otherwise required to effectstate of the art type repairs.

SUMMARY OF THE INVENTION

The noted needs, and others, are satisfied by the disclosed method,which provides for repairing a rail or rail-like structure having adefect using a single weld. The repair method according to the presentinvention begins when a rail defect is identified and located, often viause of an ultrasonic rail-testing car. Ultrasonic rail-testing is anexemplary method and/or means that can precisely locate and mark thearea of the rail containing the defect, and can confirm that the defectis totally contained in the top portion of the rail head. Additionally,manual testing of the defect may further delineate the areas of the railthat contains the defect. The top portion of the rail is then removedand the resulting section is filled by resistance welding a metal insertinto the void created for defect removal.

To accomplish the repair, the top portion of the rail containing thedefect is accurately identified and/or located by any number of means. Aspecialized apparatus is then clamped to the rail, and utilizing theapparatus, a volumetric top portion of the rail containing the defect isremoved. It is contemplated that the removal may be preferablyaccomplished by machining away a portion of the rail, for example, butother methods may be used.

Because only the top portion of the rail containing the defect isremoved, there is no appreciable change in the length of the rail andthe NRT remains unaffected. Because of the clamping action of theapparatus and the fact that only the top portion of the rail is removed,there is no need to accurately align two rails. The rail is held inacceptable alignment by the lower portion of the rail.

The welding head is then clamped to the rail. A pre-formed, solid state,weld repair insert is installed in the welding head and brought intoposition directly over the machined notch or void site. The insert ispre-machined from high quality steel that is compatible to the railsteel. The resistance welding cycle is then initiated. The weldingcurrent and platen (insert) position are precisely controlled to firstpreheat the rail and insert and then flash clean the surfaces to bewelded. Finally, the insert is forged in to the rail to create thewelding bond.

Because the rail repair is accomplished without using a rail plug, thereis no need to transport rail plugs to or away from the repair site.Additionally, the NRT of the original rail is maintained as noadditional rail or materials are or even can be added or removed fromthe existing rail length. Because only a single weld is required, andthe insertion of a rail plug is not required (as compared to other priormethods requiring two welds and plug exchange), the disclosed repairmethod is more time efficient than prior repair methods.

Given that the repair method is typically faster and does not requireadditional rail or materials, this method of repair can be performedinstead of using a joint bar splice. The repair can be accomplished inthe same track occupation as required by the detector car, therebyallowing more time of the running of revenue-producing trains. Moreover,the material characteristics and the process used to deposit the fillmaterial can provide a repair structure which has the propertiesequaling those of the rail material and far surpassing those of thethermite weld.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features of our invention will become more evident from aconsideration of the following brief description of patent drawings:

FIG. 1 is a side elevational view of a fragmentary rail length having adefect in the rail head as generically marked with an “X”.

FIG. 1( a) is transverse sectional view of the rail length otherwisedepicted in FIG. 1 as sectioned through the defect.

FIG. 2 is a side elevational view of a fragmentary rail length having adefect in the rail head as marked at “X”, which defect is beingidentified and located via certain generic defect-locating means.

FIG. 3 is a side elevational view of a fragmentary rail length having adefect in the rail head as marked at “X”, which defect has been targetedfor removal as contained within a volumetric upper rail portion asdepicted with broken lines.

FIG. 4 is a side elevational view of a fragmentary rail length showingthe marked volumetric upper rail portion otherwise depicted in FIG. 3being removed.

FIG. 4( a) is an enlarged fragmentary view as sectioned from FIG. 4depicting the angled surfaces of the void site with a beveled valleytherebetween.

FIG. 5 is a longitudinal or axial view of a rail length as supported bygeneric support structure, and engaged with certain elements of a railbus assembly in inferior adjacency to certain elements of an insert busassembly as outfitted with a repair insert.

FIG. 6 is a side elevational view of the structures otherwiseillustrated in FIG. 5, which view depicts a fragmentary rail length assupported by generic support structure and engaged with certain elementsof rail bus assembly in inferior adjacency to certain elements of aninsert bus assembly as outfitted with a repair insert.

FIG. 7 is a longitudinal or axial view of the structures otherwisedepicted in FIG. 5, which view depicts the rail length engaged withcertain elements of the rail bus assembly and the repair insert, whichrepair insert is further engaged with certain elements of the insert busassembly.

FIG. 8 is a side elevational view of the structures otherwiseillustrated in FIG. 6, which view depicts the fragmentary rail lengthengaged with the repair insert, which repair insert is further engagedwith certain elements of the insert bus assembly.

FIG. 9 is a top exploded perspective view of the structural elementsotherwise depicted in FIGS. 5 and 6.

FIG. 10 is a top perspective view of the structural elements otherwisedepicted in FIGS. 5 and 6, which elements are shown in assembled form.

FIG. 11 is a bottom perspective view of an exemplary repair insertaccording to the present invention.

FIG. 12 is a side view of the exemplary repair insert otherwise depictedin FIG. 11.

FIG. 12( a) is an enlarged fragmentary view as sectioned from FIG. 12depicting the angled surfaces of the repair insert with a beveled tiptherebetween.

FIG. 13 is a side view of the exemplary repair insert otherwise depictedin FIGS. 11 and 12 as inserted into a void site formed in a fragmentaryupper rail portion before the weld cycle is initiated.

FIG. 14 is a top view of the exemplary repair insert otherwise depictedin FIGS. 11-13 as inserted into a void site formed in a fragmentaryupper rail portion.

FIG. 15( a) is an end view of the exemplary repair insert otherwisedepicted in FIGS. 11 and 12.

FIG. 15( b) is a longitudinal or axial view of the rail length otherwisedepicted in FIGS. 13 and 14.

FIG. 15( c) is a longitudinal or axial view of the insert and railstructures otherwise depicted in FIGS. 13 and 14.

FIG. 16 is a side view of (1) the repair insert as inserted into andwelded to the void site after the weld cycle has completed, and (2) ageneric shear die cutting element removing excess insert, rail, andflash material from the fragmentary rail length.

FIG. 17 is a side elevational view of a fragmentary rail length having afinished repair site, which repair site is marked with thin brokenlines.

FIG. 18 is an enlarged fragmentary diagrammatic depiction of therail-to-insert interface having an exaggerated gap and showingorthogonally opposed planes of the interface extending from a beveledjunction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT/METHODOLOGY

Referring now to the drawings with more specificity, the reader isdirected to FIG. 1, which figure depicts a side elevational view of afragmentary rail section or length as referenced at 10. A rail length 10is typically formed having a rail base portion 11 with opposed flanges12, an upstanding rail web portion 13 extending upward from the baseportion 11 between the flanges 12, and a rail head portion 14 at the topof the rail web portion 13 as generally and comparatively depicted inFIGS. 1 and 1( a).

The repair system or method according to the present inventioneffectively begins when a rail defect 15 is identified and located, suchas by way of ultrasonic rail-testing. Ultrasonic rail-testing canprecisely locate and mark the area of rail 10 containing the defect 15.Additionally, manual testing of the defect 15 may further delineate theareas of the rail 10 which contain the defect 15. The ultrasonictesting, as exemplary defect locating means, can further confirm thatthe defect 15 is totally contained in the top portion or rail head 14 ofthe rail 10.

Further referencing FIG. 1, it will be noted that at the upper portionor head 14 of rail section 10, a generic “X” marks a defect spot or areaas at 15. While it has been noted that a rail defect 15 may bepreferably located by ultrasonic rail testing, it is contemplated thatthe rail defect 15 may be located by other rail defect identifying orlocating means such as induction means, dye penetration means or otherknown methods of defect identification.

Typically, when the ultrasonic rail testing vehicle identifies a defect,it will mark the defect location. The defect location may be recorded ona map, or a nozzle may mark the rail, for example, with paint.Alternatively, the location of the defect may be recorded usinginformation gathered from such sources as the global positioning systemof the network of satellites. FIG. 2 attempts to depict the step ofdefect identification and/or location via generic defectidentifying/locating means as referenced at 16.

After the defect location has been identified, a repair crew will bedispatched to the defect location. It is contemplated that the repaircrew will travel to the defect location with certain means for removingmaterial from the rail as well as certain means for welding a repairinsert 21 to the rail length 10. When the repair crew arrives at thedefect location, it may perform further tests to delineate the exactsize of the rail defect 15. Presuming the defect 15 is of limited sizeand localized to a select rail portion (typically the head 14), thedefect 15 may be repaired using the method according to the presentinvention.

In this regard, it is contemplated that the preferred methodologyincludes the removal of a wedge-shaped portion 17 from the rail length10, which wedge-shaped portion 17 is outlined before removal andhighlighted with broken lines 18 in FIG. 3. Notably, the wedge-shapedportion 17 includes, contains, or surrounds the rail defect 15. It willbe seen from a comparative inspection of FIGS. 3 and 4 that thewedge-shaped portion 17 has a depth 19 sufficient to include atransverse cross-section of (a) the entire head 14 as well as (b) anupper portion of the rail web 13.

The wedge-shaped void or void site 20 is preferably formed in the raillength 10 or similar other targeted metallic rail-like structure suchthat the void 20 essentially defines a pointed, insert-receiving notchorthogonally into the rail length 10 away from the planar upper railhead surface 50. The pointed insert-receiving notch or void site 20preferably further comprises orthogonally opposed planar void sitesurfaces as referenced at 51 such that the angle subtended intermediatethe planar upper rail head surface 50 and the planar surfaces 51 issubstantially 45 degrees, which angle is generally referenced at 131 inFIG. 4( a).

It is contemplated that the wedge-shaped portion 17 may be removed fromthe rail length 10 by any number of portion or material-removing meansas exemplified by certain machining means (e.g. carbide-tipped machiningmeans and electric discharge machining (EDM) means) or abrasive means.The material-removing means are operated to remove the wedge-shapedportion 17 from the rail length 10 inclusive of the defect 15. Thereader may note that the process is somewhat akin to drilling outdecayed dental material.

The analogy holds true but for the fact that the material removed fromthe rail length 10 according to the present invention tends to be of amore pre-defined volume. In other words, whereas the removal of(healthy) dental material is generally minimized during the removal ofdecayed dental material, the volumetric removal of the wedge-shapedportion 17 is (substantially) pre-determined and defined to cooperatewith pre-formed insert(s) having a pre-determined volume greater inmagnitude than the volume of material removed or defined by the voidsite 20 as generally depicted in FIGS. 4 and 6.

In other words, after the wedge-shaped, defect-containing portion 17 ofthe rail length 10 is removed, the rail length 10 is left with asubstantially wedge-shaped void site as at 20. As illustrated, anexemplary upper rail portion 17 of the rail length 10 is removed, whichportion 17 preferably includes selected portions of the rail headportion 14 and rail web portion 13. Notably, the rail length 10 is notcompletely severed, but is still connected opposite the void site 20 asonly a select (upper) portion 17 of the rail length 10 has been removed.

Because only the select (upper) portion 17 of the rail 10 is removed(i.e. that portion corresponding to the volumetric material removal) (a)there is no substantial change in the length of the rail length 10, (b)there is no need to accurately cut rail plug lengths as would be thecase if a rail plug type repair were practiced, and (c) the NRT ismaintained. In other words, according to the present methodology, therail length 10, after removing the portion 17, is held to the pre-repairlength.

Following the removal of the wedge-shaped portion 17 from the raillength 10, a volumetric, current-conductive or solid state weld repairinsert 21 is placed into the void site 20. The repair insert 21 ispreferably pre-formed from a material substantially similar to thematerial construction of the rail length 10 (e.g. 1080 rail steel andhardened rail stock/steel, respectively). FIGS. 5 and 6 generally depictthe repair insert 21 being aligned in superior adjacency to the voidsite 20 from longitudinal and lateral views respectively. FIGS. 7 and 8generally depict the repair insert 21 inserted or otherwise placed intothe void site 20 as further seen in respective longitudinal and lateralviews.

As generally depicted in FIGS. 14 and 15( c), it is contemplated thatthe width 22 of the insert 21 at its upper portion 26 is preferablyslightly greater in magnitude than the width 23 of the rail head 14 tocompensate for slight lateral shift(s) of the insert 21 during theensuing welding cycle. From the lateral views, as generally depicted inFIGS. 12 and 13, the reader will note that the length 38 of the insert21 is also greater in magnitude relative to the maximum length 39 of theupper plane of the void site 20. The reader should further note theoverall depth 19 of the insert 21 exceeds the void depth as at 24.

The wedge-shaped, solid state weld repair insert 21 is preferably formedsuch that the insert 21 preferably has a pointed rail-opposing portionas at 60 and planar force-receiving portion as at 61. The pointedrail-opposing portion 60 thus has opposed planar insert surfaces 62,which opposed planar insert surfaces 62 are preferably and substantiallyorthogonal to one another and preferably intersecting at a beveled tip41 or terminus.

The volume of the repair insert 21 is thus greater in magnitude than theeffective volume of the void site 20. During the weld cycle, thematerial composition of the rail 10 and repair insert 21 is consumedsuch that the void site 20 is effectively filled with the materialcomposition of the repair insert 21. Excess material, whether excessflash material and/or excess insert/rail material at the repair site125, is preferably removed from the rail length 10 following the weldand optional heat treat processes.

FIG. 9 depicts an exploded perspective view of a test weld scenarioshowing the primary components that enable the present methodology. Inthis regard, the preferred system and/or method essentially employs acurrent-conductive, insert-side bus assembly for interfacing with therepair insert 21 and a current-conductive, rail-side bus assembly forinterfacing with the rail length 10.

The insert-side bus assembly preferably comprises a top bus bar as at30, a wedge or insert block as at 31, a pair of inner, opposed wedge orinsert side plates as at 32, a pair of outer side plates as at 33, and apair of cooling blocks as at 34. Cooling blocks 34 can be moved toachieve strategic cooling of the tooling and/or weld.

Opposite the insert-side bus assembly is positioned a rail-side busassembly (or assemblies). The rail length 10 is supported in FIGS. 5-10by a generic support plane or structure as referenced at 102. Therail-side bus assembly preferably comprises laterally-opposed,web-engaging rail bus elements as at 40 each of which is engaged with(a) opposed rail bus side plates as at 41 and (b) a rail bus bridge asat 42. FIGS. 7 and 8 depict current 100 being driven through the busassemblies via the repair insert 21, the rail length 10, and thestructure-to-insert interface or rail-to-insert interface 101.

A so-called flash butt weld cycle typically comprises three phases,namely, a pre-heating phase, a flashing phase, and an upsetting orforging phase by way of varied amperages ranging anywhere from 22,000amps to 47,000 amps. Excellent results, for example, have been achievedby using an electric current during (1) the pre-heating phase between32,000 and 42,000 amps, (2) the flashing phase between 27,000 and 37,000amps, and (3) the upsetting phase between 30,000 and 44,000 amps. Thenominal flashing voltage is best at about seven to ten volts, and thenominal upsetting distance is best at about 0.375 to 1.00 inch. Theforegoing amperages, voltages, and distances are exemplary and notlimiting.

Resistance from the current 100 being driven through the structuresheats the interface 101, and the repair insert 21 is thus flash-weldedto the rail length 10 at the void site 20 as generically depicted at“flashing” 105. This has the effect of forming an oxide-free, cleanjunction between the repair insert 21 and the rail length 10 as therespective surfaces of the repair insert 21 and rail length 10 areforced out the sides of the junction or rail-to-insert interface 101.FIG. 16 depicts the noted/described excess flash material as referencedat 104.

The reader will further note from an inspection of FIGS. 7 and 8 that asignificant force 103 is directed into the structures such that therepair insert 21 is forced against the rail length 10 at the void site(elsewhere referenced at 20). The ensuing/attendant heat and force 103further cause the repair insert 21 to be forge-welded to the rail length10 at the rail-to-insert interface 101, during which atomic structure ofthe rail length 10 and repair insert 21 interdiffuse to cause a robust,solid-state weld at the rail-to-insert interface 101.

As earlier introduced, the reader will note that the wedge-shaped voidsite 20 and wedge-shaped repair insert 21 provide an angledrail-to-insert interface 101. It is contemplated that a significantbenefit is achieved by way of the angled rail-to-insert interface 101.For example, the reader will note that force 103 is directed in a first(or downward) direction as depicted in the drawings. The angledrail-to-insert interface 101 is bound on the rail side by rail structurealong its entire length 39 for opposing force 103 as delivered to therail length 10 via repair insert 21. The repair inset 21 thus transfersforce 103 along that portion of length 39 in contact with the raillength 10.

Excellent results have been achieved when forming a 90 degree angle (asat 130 in FIGS. 4( a) and 18) at the void site 20 and repair insert 21.It is contemplated that the orthogonal relationship between opposingplanes 115 of the interface 101 structurally function to enhance uniformheat distribution (as diagrammatically depicted at 150 in FIG. 18) andminimize material entrapment during the welding process.

Further, the valley 40 of the void site 20 and the tip 41 of the insert21 are preferably beveled or rounded for further minimizing materialentrapment during the welding process. Excellent results have beenachieved when the radii of curvature of the beveled structures 40 and 41are on the order of 0.25 inch. Other insert geometry is believedinferior for achieving the desired result as compared to the geometryshown in the various illustrations.

FIGS. 11-15( a) depict the preferred geometry of the repair insert 21.It will be recalled that before the welding cycle begins, the repairinsert 21 has a pre-determined geometry such that the upper width 22 ofthe repair insert 21 is of slightly greater magnitude than the rail headwidth 23. It is contemplated that the upper insert width 22 should beslightly larger widthwise relative to the rail head 14 as generallydepicted to compensate for slight lateral shift under load 103. Further,it will be noted that the depth 19 of insert 21 is significantly greaterin magnitude than the depth 24 of the void site 20.

During the welding cycle, material from elements 10 and 21 are consumedsuch that the volumetric geometry of repair insert 21 is reduced as maybe understood from a comparative inspection of FIG. 13 versus 16. Theflash material 104 and excess insert material 106 is then removed (e.g.by grinding, machining, and/or sheering) after the weld cycle (andoptional quench cycle).

The repair insert 21 preferably further comprises an upperhead-approximating portion 26 and a lower web-approximating portion 27,however as a means to reduce the excess material as exemplified bymaterial(s) 104 and 106 after the weld cycle. In this regard, it iscontemplated that the upper head-approximating portion 26 preferablycomprises a width 22 slightly larger than the rail head width 24, andthe lower web-approximating portion 27 comprises a width 28 of slightlygreater magnitude than the web width 29.

Notably, the maximal transverse cross-sectional insert area as generallydepicted at 112 is preferably beveled as at 42 intermediate said upperinsert portion width 22 and said lower insert portion width 28. In thisregard, it is contemplated that the beveled structures 42 approximatebeveled structures 32 intermediate the rail head 14 and the rail web 13and thereby effectively function to minimize excess material after theweld cycle.

After the weld and optional heat treat cycles, the rail with weldedinsert site is finished by removing the flash and excess materials 104and 106, for example by shear die cutting the excess from the rail 10 asgenerically depicted at 120. The finished, repaired rail length 110 thuscomprises a virtually seamless repair site 125, which repair site 125was effected by robust weld processes per the present methodology.

Notably, the method of rail repair described hereinabove is also usefulas a method of managing the neutral rail temperature (NRT). When therail 10 is first installed the environmental conditions are within aselected range. These environmental conditions are recorded and theinitial NRT is established. When a portion of rail 10 is replaced by anew material, such as thermite or a rail segment or plug, the NRT mustthen be recalculated and tracked. By virtue of not maintaining acontinuous rail during the described method, the initial NRT ismaintained.

While specific embodiments of the invention have been described indetail, it will be appreciated by those skilled in the art that variousmodifications and alternatives to those details could be developed inlight of the overall teachings of the disclosure. For example, themethod of rail repair may be said to essentially apply to a rail 10having upper and lower rail sections, which upper rail may well comprisethe rail head 14 and a(n upper) portion of the rail web 13, whereas thelower rail section may be said to comprise the rail base 11 and a(lower) portion of the rail web 13.

Further, the method may be said to essentially comprise the steps ofinitially identifying and locating a defect in a first select railsection, which first select rail section may be selected from the groupconsisting of the upper and lower rail sections. After a defect 15 islocated, a volumetric portion (as at 17) of the rail 10 may then beremoved from the first select rail section, which volumetric portion 17includes or contains the defect 15.

By way of removal of the volumetric portion 17, a void site 20 isexposed in the first select rail section and a pre-formed metal insert21 may be placed into the void site 20, thereby effecting arail-to-insert interface as at 101. Current 100 may then be drivenacross or through the rail-to-insert interface 101 thereby heating therail 10 and insert 21 at the rail-to-insert interface 101 via resistanceof the driven current 100, which heat operates to effectivelyresistance-weld the insert 21 to the rail 10.

Notably, the continuity of a second select rail section is maintainedwhile exposing the void site, which second select rail section is alsoselected from the group consisting of the upper and lower rail sections,but which second select rail section is opposite the first select railsection. Further, as noted, the void site 20 has a maximal transversecross-sectional site area as generally referenced at 111 and the insert21 has a maximal transverse cross-sectional insert area as generallyreferenced at 112. Said insert area 112 is preferably greater inmagnitude than said site area 111, but approximate thereto so as tominimize the volume of excess material that must be removed during thefinishing step(s).

The method may be said to further comprise the steps of forcing theinsert 21 against the rail 10 while driving current across therail-to-insert interface 101; removing oxides from the rail-to-insertinterface 101 during the step of flash welding the insert 21 to the rail10; and interdiffusing atomic structure of the rail 10 and insert 21across or through the rail-to-insert interface 101 while forge weldingthe insert 21 to the rail length 10.

The foregoing methods are believed to systemically follow from theunderlying rail and repair insert combination, which combination may besaid to comprise a certain rail length 10 and a repair insert as at 21.The rail length 10 as generally depicted throughout the illustrationshas a rail head portion 14, a rail web portion 13, a rail base portion11, and a void site 20 formed therein to remove a rail defect 15. Thevoid site 20 is located intermediate the rail length and preferablyextends into the rail head and web portions 14 and 13. The void site 20has a maximal site depth as at 24 and a maximal site length as at 39.

The repair insert 21 is insertable into the void site 20 for effecting arail-to-insert interface as at 101. The repair insert 21 comprises anupper insert portion 26, a lower insert portion 27, a maximal insertdepth as at 19, and a maximal insert length as at 38. The insert depth19 is greater in magnitude than the site depth 24 and the insert length38 is greater in magnitude than the site length 39. Both the rail length10 and the repair insert 21 are preferably formed from weldablematerials and are thus weldable to one another substantially asdescribed hereinabove, although other solid state welding techniquessuch as friction welding and brazing are contemplated.

Notably, the void site 20 preferably has a wedge-shaped, longitudinalsite cross-section as generally depicted in FIGS. 4 and 6; and therepair insert 21 preferably has a wedge-shaped, longitudinal insertcross-section as generally depicted in FIGS. 12 and 13. The wedge-shapedlongitudinal site and insert cross-sections preferably comprisesubstantially 90 degree angles 130 at the rail-to-insert interface 101,and respectively comprise a beveled valley as at 40 and tip as at 41 forminimizing material entrapment during the welding process.

From a comparative inspection of FIGS. 15( a)-15(c), it will be seenthat the upper insert portion 26 preferably comprises a substantiallyuniform upper insert portion width as at 22, the lower insert portion 27has a substantially uniform lower insert portion width as at 28, therail head portion 14 has a maximum head width as at 23, and the rail webportion 13 has a substantially uniform web width as at 29.

The upper insert portion width 22 is preferably greater in magnituderelative to the lower insert portion width 28 and the head width 23. Thelower insert portion width 28 is preferably lesser in magnitude than thehead width 23, but greater in magnitude than then web width 29. Themaximal transverse cross-sectional insert area 112 is preferably beveledintermediate said upper insert portion width 22 and said lower insertportion width 28.

Accordingly, although the invention has been described by reference tocertain preferred and alternative embodiments and methodologies, it isnot intended that the novel disclosures and methods herein presented belimited thereby, but that modifications thereof are intended to beincluded as falling within the broad scope and spirit of the foregoingdisclosure, the following claims and the appended drawings.

We claim:
 1. A method of repairing a metallic structure having first andsecond structural sections, the method comprising the steps of: a)identifying and locating a defect in the metallic structure; b) removinga volumetric portion from the first structural section, the volumetricportion being inclusive of the defect; c) exposing a void site in thefirst structural section via removal of the volumetric portion; d)placing a pre-formed, solid state weld repair insert into the void site,thereby effecting a structure-to-insert interface; and e) welding themetallic structure and insert at the structure-to-insert interface. 2.The method of claim 1 wherein the welding step comprises the step ofdriving current through the structure-to-insert interface.
 3. The methodof claim 1 comprising the step of maintaining continuity of the secondstructural section while exposing the void site.
 4. The method of claim3 wherein the volumetric portion has a first volume and the insert has asecond volume greater in magnitude relative to the first volume.
 5. Themethod of claim 4 comprising the step of forcing the insert against themetallic structure during the welding process.
 6. The method of claim 5comprising the step of removing oxides from the structure-to-insertinterface during the welding process.
 7. The method of claim 6comprising the step of interdiffusing atomic structure from the metallicstructure and insert across the structure-to-insert interface.
 8. Themethod of claim 7 wherein the metallic structure is a rail.
 9. A methodof repairing a current-conductive rail, which rail includes upper andlower rail sections, the method comprising the steps of: a) identifyingand locating a defect in a first select rail section, the first selectrail section being selected from the group consisting of the upper andlower rail sections; b) removing a volumetric portion of the rail fromthe first select rail section, the volumetric portion being inclusive ofthe defect; c) exposing a void site in the first select rail section viaremoval of the volumetric portion; d) placing a pre-formedcurrent-conductive insert into the void site, thereby effecting arail-to-insert interface; e) driving current through the rail-to-insertinterface; f) resistance-heating the rail and insert at therail-to-insert interface via the driven current; and g) welding theinsert to the rail.
 10. The method of claim 9 comprising the step ofmaintaining continuity of a second select rail section while exposingthe void site, the second select rail section being selected from thegroup consisting of the upper and lower rail sections and being otherthan the first select rail section.
 11. The method of claim 10 whereinthe volumetric portion has a first volume and the insert has a secondvolume greater in magnitude relative to the first volume.
 12. The methodof claim 11 wherein the void site has a maximal transversecross-sectional site area and the insert has a maximal transversecross-sectional insert area, said insert area being greater in magnitudethan said site area.
 13. The method of claim 9 comprising the step offorcing the insert against the rail while driving current through therail-to-insert interface.
 14. The method of claim 9 comprising the stepof removing oxides from the rail-to-insert interface.
 15. The method ofclaim 13 comprising the step of interdiffusing atomic structure of therail and insert across the rail-to-insert interface.
 16. The method ofclaim 12 wherein said insert area is minimized relative to said sitearea.
 17. A method of repairing a current-conductive rail, said methodcomprising the steps of: a) removing a defect-inclusive, volumetric railportion from said rail; b) exposing a void site in said rail via removalof said rail portion; c) placing a pre-formed current-conductive insertinto the void site, thereby effecting a rail-to-insert interface; and d)driving current through the rail-to-insert interface, thereby heatingthe rail and insert at the rail-to-insert interface and welding theinsert to the rail.
 18. The method of claim 17 comprising the step ofmaintaining continuity of the rail adjacent the void site while exposingthe void site.
 19. The method of claim 18 comprising the step of forcingthe insert against the rail while driving current through therail-to-insert interface, thereby a. removing oxides from therail-to-insert interface; and b. interdiffusing atomic structure of therail and insert across the rail-to-insert interface.
 20. A rail repairmethod, the method comprising the steps of: forming a wedge-shapedrepair insert having a pointed rail-opposing portion, the pointedrail-opposing portion having opposed planar insert surfaces, the opposedplanar insert surfaces being substantially orthogonal to one another;forming a wedge-shaped void in a rail, the void having a pointed,insert-receiving notch, the pointed insert-receiving notch havingopposed planar void site surfaces, the void site surfaces beingsubstantially orthogonal to one another; inserting the wedge-shapedrepair insert into the wedge-shaped void thereby effecting an angledrail-to-insert interface, the angled rail-to-insert interface thushaving a 90 degree angle; and driving current through the rail-to-insertinterface for heating and welding the rail and insert at therail-to-insert interface, the 90 degree angle for enhancing uniform heatdistribution and minimizing material entrapment during the weldingprocess.
 21. The method of claim 20 wherein the current driving stepcomprises the steps of: preheating the rail and repair insert by drivinga first range of current therethrough; flashing the rail and repairinsert by driving a second range of current therethrough; and forgingthe rail and repair insert by driving a third range of currenttherethrough.
 22. The method of claim 21 wherein the repair insertforming step comprises the added step of forming a beveled tipintermediate the opposed planar insert surfaces and the void formingstep comprises the added step of forming a beveled valley intermediatethe opposed planar void site surfaces, the beveled tip and beveledvalley for further minimizing material entrapment during the weldingprocess.
 23. A method of repairing a metallic structure, the methodcomprising the steps of: a) identifying and locating a defect in themetallic structure; b) removing a volumetric portion from first andsecond structural sections of the metallic structure, the firststructural section being integrally formed to the second structuralsection, the volumetric portion being inclusive of the defect; c)exposing a void site in the first and second structural sections viaremoval of the volumetric portion; d) placing a pre-formed, solid stateweld repair insert into the void site, thereby effecting astructure-to-insert interface, the insert comprising an insert volumegreater in magnitude than the removed volumetric portion; and e) weldingthe metallic structure and insert at the structure-to-insert interface.24. The method of claim 23 comprising the steps of forcing the inserttoward the first and second structural sections for forging the insertto the metallic structure at the structure-to-insert interface whilewelding the metallic structure and insert at the structure-to-insertinterface.
 25. The method of claim 24 wherein the volumetric portion andinsert volume are T-shaped in a first dimension, triangular in a seconddimension, and rectangular in a third dimension.
 26. The method of claim25 wherein the T-shaped volumetric portion comprises rounded upperedging and the T-shaped insert volume comprises right-angled upperedging.
 27. The method of claim 26 wherein the triangular volumetricportion and the insert volume each comprise a rounded interface vertex.28. A method of repairing a current-conductive rail, which rail includesupper and lower rail sections, the method comprising the steps of: a)identifying and locating a defect in a first select rail section, thefirst select rail section being selected from the group consisting ofthe upper and lower rail sections; b) removing a volumetric portion ofthe rail from the first select rail section, the volumetric portionbeing inclusive of the defect; c) exposing a void site in the firstselect rail section via removal of the volumetric portion; d) placing apre-formed current-conductive insert into the void site, therebyeffecting a rail-to-insert interface, the insert comprising an insertvolume greater in magnitude than the removed volumetric portion; e)driving current through the rail-to-insert interface; f)resistance-heating the rail and insert at the rail-to-insert interfacevia the driven current; and g) welding the insert to the rail.
 29. Themethod of claim 28 comprising the steps of forcing the insert toward theupper and lower rail sections for forging the insert to the rail at therail-to-insert interface while welding the insert to the rail.
 30. Themethod of claim 28 wherein the volumetric portion and insert volume areT-shaped in a first dimension, triangular in a second dimension, andrectangular in a third dimension.
 31. The method of claim 30 wherein theT-shaped volumetric portion comprises rounded upper edging and theT-shaped insert volume comprises right-angled upper edging.
 32. Themethod of claim 31 wherein the triangular volumetric portion and theinsert volume each comprise a rounded interface vertex.
 33. A method ofrepairing a current-conductive rail, said method comprising the stepsof: a) removing a defect-inclusive, volumetric rail portion from upperportions of said rail; b) exposing a void site in said rail via removalof said rail portion; c) placing a pre-formed current-conductive insertinto the void site, thereby effecting a rail-to-insert interface, theinsert comprising an insert volume greater in magnitude than the removedvolumetric portion; and d) driving current through the rail-to-insertinterface, thereby heating the rail and insert at the rail-to-insertinterface and welding the insert to the rail.
 34. The method of claim 33comprising the steps of forcing the insert toward the upper portions forforging the insert to the rail at the rail-to-insert interface whilewelding the insert to the rail.
 35. The method of claim 33 wherein thevolumetric portion and insert volume are T-shaped in a first dimension,triangular in a second dimension, and rectangular in a third dimension.36. The method of claim 35 wherein the T-shaped volumetric portioncomprises rounded upper edging and the T-shaped insert volume comprisesright-angled upper edging.
 37. The method of claim 36 wherein thetriangular volumetric portion and the insert volume each comprise arounded interface vertex.
 38. A rail repair method, the methodcomprising the steps of: forming a wedge-shaped repair insert, theinsert being T-shaped in a first dimension, triangular in a seconddimension, and rectangular in a third dimension, the triangular seconddimension having a pointed rail-opposing portion, the pointedrail-opposing portion having opposed planar insert surfaces, the opposedplanar insert surfaces being substantially orthogonal to one another;forming a wedge-shaped void in a rail, the void being T-shaped in thefirst dimension, triangular in the second dimension, and rectangular inthe third dimension, the void having a pointed, insert-receiving notch,the pointed insert-receiving notch having opposed planar void sitesurfaces, the void site surfaces being substantially orthogonal to oneanother; inserting the wedge-shaped repair insert into the wedge-shapedvoid thereby effecting an angled rail-to-insert interface, the angledrail-to-insert interface thus having a 90 degree angle; and drivingcurrent through the rail-to-insert interface for heating and welding therail and insert at the rail-to-insert interface, the 90 degree angle forenhancing uniform heat distribution and minimizing material entrapmentduring the welding process.
 39. The method of claim 38 comprising thesteps of forcing the insert toward the rail for forging the insert tothe rail at the rail-to-insert interface while welding the insert to therail.
 40. The method of claim 38 wherein the T-shaped dimension of theinsert comprises right-angled upper edging, and the T-shaped dimensionof the void comprises rounded upper edging.
 41. The method of claim 40wherein the triangular dimension of the insert and void each comprise arounded interface vertex.